[PATCH v3 3/3] ARM: Check if a CPU has gone offline

[Rob Herring]

On Thu, Mar 27, 2014 at 4:23 PM, Ashwin Chaugule
<ashwin.chaugule at linaro.org> wrote:
> PSCIv0.2 adds a new function called AFFINITY_INFO, which
> can be used to query if a specified CPU has actually gone
> offline. Calling this function via cpu_kill ensures that
> a CPU has quiesced after a call to cpu_die.
>
> Signed-off-by: Ashwin Chaugule <ashwin.chaugule at linaro.org>

One minor nit, but otherwise:

Reviewed-by: Rob Herring <robh at kernel.org>

> ---
>  arch/arm/kernel/psci_smp.c | 21 +++++++++++++++++++++
>  include/uapi/linux/psci.h  |  5 +++++
>  2 files changed, 26 insertions(+)
>
> diff --git a/arch/arm/kernel/psci_smp.c b/arch/arm/kernel/psci_smp.c
> index 570a48c..4c1adf9 100644
> --- a/arch/arm/kernel/psci_smp.c
> +++ b/arch/arm/kernel/psci_smp.c
> @@ -16,6 +16,7 @@
>  #include <linux/init.h>
>  #include <linux/smp.h>
>  #include <linux/of.h>
> +#include <uapi/linux/psci.h>
>
>  #include <asm/psci.h>
>  #include <asm/smp_plat.h>
> @@ -66,6 +67,25 @@ void __ref psci_cpu_die(unsigned int cpu)
>         /* We should never return */
>         panic("psci: cpu %d failed to shutdown\n", cpu);
>  }
> +
> +int __ref psci_cpu_kill(unsigned int cpu)
> +{
> +       int err;
> +
> +       if (!psci_ops.affinity_info)
> +               return 1;
> +
> +       err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
> +
> +       if (err != PSCI_AFFINITY_INFO_RET_OFF) {
> +               pr_err("psci: Cannot kill CPU:%d, psci ret val: %d\n",
> +                               cpu, err);
> +               /* Make platform_cpu_kill() fail. */
> +               return 0;
> +       }
> +       return err;

I think this should just be "return 1;" PSCI_AFFINITY_INFO_RET_OFF
happens to match, but it's really different meanings.

> +}
> +
>  #endif
>
>  bool __init psci_smp_available(void)
> @@ -78,5 +98,6 @@ struct smp_operations __initdata psci_smp_ops = {
>         .smp_boot_secondary     = psci_boot_secondary,
>  #ifdef CONFIG_HOTPLUG_CPU
>         .cpu_die                = psci_cpu_die,
> +       .cpu_kill               = psci_cpu_kill,
>  #endif
>  };
> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
> index c523051..2c177f5 100644
> --- a/include/uapi/linux/psci.h
> +++ b/include/uapi/linux/psci.h
> @@ -37,4 +37,9 @@
>  #define PSCI_RET_EINVAL                        -2
>  #define PSCI_RET_EPERM                 -3
>
> +/* Return values from the PSCI_ID_AFFINITY_INFO Function. */
> +#define PSCI_AFFINITY_INFO_RET_ON                      0
> +#define PSCI_AFFINITY_INFO_RET_OFF                     1
> +#define PSCI_AFFINITY_INFO_RET_ON_PENDING      2
> +
>  #endif /* _UAPI_LINUX_PSCI_H */
> --
> 1.8.3.2
>